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Zintl phases are excellent candidates for high-efficiency thermoelectrics (TEs) due to their extremely low lattice thermal conductivity. The manufacturing of an all-Zintl module is particularly att...

In this work, we discover anomalously low lattice thermal conductivity (

Zintl phases are promising thermoelectric materials because they are composed of both ionic and covalent bonding, which can be independently tuned. An efficient thermoelectric material would have regions of the structure composed of a high-mobility compound semiconductor that provides the “electron–crystal” electronic structure, interwoven (on the atomic scale) with a phonon transport inhibiting structure to act as the “phonon–glass”. The phonon–glass region would benefit from disorder and therefore would be ideal to house dopants without disrupting the electron–crystal region. The solid solution of the Zintl phase, Yb2–xEuxCdSb2, presents such an optimal structure, and here we characterize its thermoelectric properties above room temperature. Thermoelectric property measurements from 348 to 523 K show high Seebeck values (maximum of ∼269 μV/K at 523 K) with exceptionally low thermal conductivity (minimum ∼0.26 W/m K at 473 K) measured via laser flash analysis. Speed of sound data provide additional suppo...

In this work, we present an exfoliation method that produces cm2-area atomically flat surfaces from bulk layered single crystals, with broad applications such as for the formation of lateral heterostructures and for use as substrates for van der Waals epitaxy. Single crystals of Bi2Se3 were grown using the Bridgman method and examined with X-ray reciprocal space maps, Auger spectroscopy, low-energy electron diffraction, and X-ray photoelectron spectroscopy. An indium-bonding exfoliation technique was developed that produces multiple ∼100 μm thick atomically flat, macroscopic (>1 cm2) slabs from each Bi2Se3 source crystal. Two-dimensional X-ray diffraction and reciprocal space maps confirm the high crystalline quality of the exfoliated surfaces. Atomic force microscopy reveals that the exfoliated surfaces have an average root-mean-square (RMS) roughness of ∼0.04 nm across 400 μm2 scans and an average terrace width of 70 μm between step edges. First-principles calculations reveal exfoliation energies of Bi2...

Zn–Sb compounds (e.g., ZnSb, β-Zn13Sb10) are known to have intriguing thermoelectric properties, but studies of the Zn3Sb2 composition are largely absent. In this work, α-Zn3Sb2 was synthesized and studied via temperature-dependent synchrotron powder diffraction. The α-Zn3Sb2 phase undergoes a phase transformation to the β form at 425 °C, which is stable until melting at 590 °C. Rapid quenching was successful in stabilizing the α phase at room temperature, although all attempts to quench β-Zn3Sb2 were unsuccessful. The structure of α-Zn3Sb2 was solved using single crystal diffraction techniques and verified through Rietveld refinement of the powder data. α-Zn3Sb2 adopts a large hexagonal cell (R 3 space group, a = 15.212(2), c = 74.83(2) A) containing a well-defined framework of isolated Sb3– anions but highly disordered Zn2+ cations. Dense ingots of both the α-Zn3Sb2 and β-Zn13Sb10 phases were formed and used to characterize and compare the low temperature thermoelectric properties. Resistivity and Seeb...

The rise of high-throughput calculations has accelerated the discovery of promising classes of thermoelectric materials. In prior work, we identified the n-type Zintl pnictides as one such material class. To date, however, a lack of detailed defect calculations and chemical intuition has led the community to investigate p-type Zintls almost exclusively. Here, we investigate the synthesis, thermoelectric properties, and defect structure of the complex Zintl KGaSb4. We find that KGaSb4 is successfully doped n-type with Ba and has the potential for p-type doping with Zn. Our calculations reveal the fundamental defect structure in KGaSb4 that enables n-type and p-type doping. We find that Ba doped KGaSb4 exhibits high electronic mobility (∼50 cm2V–1s–1) and near minimum lattice thermal conductivity ( 0.9 at 400 °C, promising for a previously unstudied material. We also briefly investigate the series of alloys between KGaSb4 and KAlSb4, finding th...

High-throughput, low-cost, and accurate predictions of thermal properties of new materials would be beneficial in fields ranging from thermal barrier coatings and thermoelectrics to integrated circuits. To date, computational efforts for predicting lattice thermal conductivity (κL) have been hampered by the complexity associated with computing multiple phonon interactions. In this work, we develop and validate a semiempirical model for κL by fitting density functional theory calculations to experimental data. Experimental values for κL come from new measurements on SrIn2O4, Ba2SnO4, Cu2ZnSiTe4, MoTe2, Ba3In2O6, Cu3TaTe4, SnO, and InI as well as 55 compounds from across the published literature. To capture the anharmonicity in phonon interactions, we incorporate a structural parameter that allows the model to predict κL within a factor of 1.5 of the experimental value across 4 orders of magnitude in κL values and over a diverse chemical and structural phase space, with accuracy similar to or better than th...